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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 984 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.?714 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.890? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 68 and take away the sum of its digits. What do you get?
  4. 4.?166 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?791 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.377? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 67 and take away the sum of its digits. What do you get?
  8. 8.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 28 and take away the sum of its digits. What do you get?
  10. 10.Take 65 and take away the sum of its digits. What do you get?
  11. 11.579? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 47 and take away the sum of its digits. What do you get?
  13. 13.Take 83 and take away the sum of its digits. What do you get?
  14. 14.499? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?320 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 57 and take away the sum of its digits. What do you get?
  17. 17.356? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.77?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 42 and take away the sum of its digits. What do you get?
  20. 20.461? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.74?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.246? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 88 and take away the sum of its digits. What do you get?
  24. 24.Take 20 and take away the sum of its digits. What do you get?
  25. 25.?277 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.11?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.6?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 23 and take away the sum of its digits. What do you get?
  29. 29.826? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.5?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 70 and take away the sum of its digits. What do you get?
  34. 34.Take 60 and take away the sum of its digits. What do you get?
  35. 35.5?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 43 and take away the sum of its digits. What do you get?
  37. 37.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.27?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.4?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 29 and take away the sum of its digits. What do you get?

Answer key

  1. 6
  2. 1
  3. 54
  4. 5
  5. 1
  6. 1
  7. 54
  8. 3
  9. 18
  10. 54
  11. 6
  12. 36
  13. 72
  14. 5
  15. 4
  16. 45
  17. 4
  18. 7
  19. 36
  20. 7
  21. 5
  22. 6
  23. 72
  24. 18
  25. 2
  26. 3
  27. 7
  28. 18
  29. 2
  30. 9
  31. 4
  32. 4
  33. 63
  34. 54
  35. 2
  36. 36
  37. 6
  38. 2
  39. 8
  40. 18

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